Process for blending alkyd resin and ether of dimethylol urea



Patented Feb. 13, 1951 UNITED STATES PATENT OFFICE PROCESS FOR BLENDINGALKYD RESIN AND ETHEE OF DIMETHYLOL UREA Herbert 3. West, Pittsburgh,Pa., assignor to American Cyanamid Company, New York, N. Y.,

a corporation of Maine No Drawing. Application July 18, 1947, Serial No.761,992

14 Claims. 1

This application is a continuation-in-part of 'my copending applicationSerial No. 427,025, filed January 16, 1942, and now abandoned.

This invention relates to resinous compositions and to methods ofpreparing the same, and more particularly to the production of blends ofalkyd resins with others of dimethylol urea and, specifically, with thedimethyl ether of dimethylol urea, which also may be namedbis(methoxymethyl) urea. The invention is especially concerned with theproduction of compositions comprising a homogeneous blend, which issoluble in an aromatic hydrocarbon (e. g., benzene, toluene, xylene,etc.) of (1) an alkyd resin which is soluble in an aromatic hydrocarbonand (2) a partial condensation polymer of dimethyl ether of dimethylolurea, which polymer has been polymerized to a degree corresponding tothe liberation of, by Weight, not more than about 35%, more particularlyfrom about 5 to about 30%, e. g., about of methanol (combined methanol)from the said ether, that is, from the total mass of other which hasbeen polymerized. Such compositions are prepared by dissolving in analkyd resin of the kind aforementioned a substance of the classconsisting of dimethyl ether of dimethylol urea (more particularlycrystalline dimethyl ether of dimethylol urea) and partial condensationpolymers thereof, which have been polymerized to the above-describeddegree, by heating a mixture of the said substance and the said resinuntil there has been formed a homogeneous blend which is soluble in anaromatic hydrocarbon. The dimethyl ether of dimethylol urea or thepartial condensation polymer there of as present in the said blend ispolymerized to a degree corresponding to the liberation of not more thanabout 35% by weight of methanol from the said ether.

Many and varyin processes have been sug-.

gested and used for blending alkyd resins with alkylatedurea-formaldehyde resins. In general, it has been found that thecompatibility of the alkylated urea-formaldehyde resins with the alkydresins, especially those modified with oil acids, decreases with themolecular weight of the alcohol used for alkylation of theurea-formaldehyde resin. Thus the propylated urea-formaldehyde resin areless compatible with alkyd resins than the butylated resins and theethylated resins have an even more limited range of compatibility.Therefore, it would be indicated that the methylated urea-formaldehyderesins are even less compatible with alkyd resins.

As set forth in my application Serial No.

404,203, filed July 26, 1941, now Patent No. 2,397,825, issued April 2,1946, of which the aforementioned application SerialNo. 427,025 is acontinuation-in-part, I have found that the alkyl ethers of dimethylolurea, including the dimethyl ether of dimethylol urea, may be blendedwith alkyd resins to form valuable coating compositions, The blends areclear, stable compositions which are soluble in aromatic hydrocarbonsand have other outstanding and unexpected properties. The resultsobtained are even more surprising since the others are substantiallyinsoluble in aromatic hydrocarbons, but the blends of the ethers withthe alkyd resins are soluble in aromatic hydrocarbons.

Various methods may be employed in carrying my invention into effect.For example, I may polymerize the dimethyl ether of dimethylol urea to adegree or extent corresponding to the liberation of not more than about35%, more particularly from about 1 to about 35%, by weight of methanol(combined methanol) from the said ether, that is, I may prepare acondensation polymer of dimethyl ether of dimethylol urea which has beennot more than about 35% demethylated (demethanolated) ,mix the resultingpolymer with an alkyd resin which is soluble in an aromatic hydrocarbonand which may be either in molten or solution state, and heat themixture thereby obtained, e. g., at from about 55 C. to about 100 (3.,preferably at from about or C. to about or C., until there has beenformed a homogeneous blend which is soluble in an aromatic hydrocarbon.If desired, instead of pre-polymerizing the dimethyl ether of dimethylolurea before mixing it with the alkyd resin, ll may mix the substantiallyunpolymerized dimethyl ether, e. g. substantially pure or crystallinedimethyl ether of dimethylol urea, with the alkyd resin in molten orsolution state, and heat the resulting mixture as above described. Thedimethyl ether is polymerized during this heating to a degreecorresponding to the liberation of not more than about 35% by weight ofmethanol therefrom; I prefer to pre-polymerize the dimethyl ether priorto mixing it with the alkyd resin, since a shorter heating period isrequired and less difiiculty is encountered in obtaining a homogeneousblend than when the unpolymerized other is mixed with the resin.

As indicated hereinbefore, the polymerized or unpolymerized dimethylether of dimethylol urea may be mixed either with the molten alkyd resinor with a solution thereof (e. g., a solution of the resin in anaromatic hydrocarbon), after which trays or the like and allowed to"harden.

the mixture is heated as above described. Heating is continued until theadded polymer or the polymer which is formed in situ dissolves in theresin or resin solution, and a homogeneous blend, a sample of whichremains clear on cooling, is obtained. The blend issoluble in aromatichydrocarbons, examples of which have been given hereinbefore.

In order that those skilled in the art better may understand how thepresent invention may be carried into effect, the following examples aregiven by way of illustration and. not by way of limitation. All partsand, percentages are: by weight.

EXAMPLE 1 Ether A barium oxalate and thereby remove the oxalic acid fromthe solution. A slight excess of barium hydroxide is used" to give a pH-of 7.5-8.0'. The precipitated; bariumoxalate is removed by filtrationand the filtrate is concentrated in vacuo.

(26,-2l inches). by heating to a, temperature not exceeding 50 C'. Theconcentration is continued until the solution contains about 60% solids,at whichpointthe greater part of the excess methyl alcohol andwater willhave been removed.

The ether solution is further concentrated in vacuo' as above, theheating and concentration being continued: until a, temperature of about90-" C. is reached. 7 Atthis time the last traces of water are removed.by adding toluene in an.

of the calcuamount equal. to about l'atedf' yield; and distillation iscontinued in vacuo. at about 80 C. until the toluene and water areremoved. The resultant product is, aclear 'melt which may then be dumpedin The nitrogen. content ofthisresinous 0r semi-crystalline. productindicates that it has been polymerizedto a degree corresponding to theliberation of; about 11% of methanol from the ether.

A'llcyd resin B Parts Ether A Alkyd resin B '75 The. alkyd. resin ispremelted and heated to about 70 C. and the other is added withstirring, the temperature being maintained until the mixture ishomogeneous as indicated by the. fact that a.pill removed from. thebatch will. remain clear on' cooling. At this time, the blend may. bepoured into suitable trays and allowed to: cool,

be stored and shipped. For use, as in a coating composition, the resinneed merely be remelted and dissolved, while hot, in a suitable solventto the desired solids content. Alternatively, the hot blend prepared asdescribed above may be out. directly, while hot, with a solvent such asxylene or toluene to the desired solids content and the solution thusprepared may be stored and shipped as expedient.

EXAMPLE 2 Ether C' This: ether is prepared following the procedure setforth under Example 1 with the reference to- Ether A down through theperiod of heating at a temperature not exceeding C. At this point,instead of raising the temperature, there whereupon a solid. resin isformed which. may

is added to the concentrated solution an equal part of toluene andthedistillation is continued to remove any remaining water anduncombined methyl alcohol; The methanol. and water free mixture isobtained as a slurry since the ether crystals are insoluble: in toluene.The slurr is filtered andv the crystals. dried to remove any adheringtoluene. Throughout these operations the temperature of the materials ismaintained below 50 C. Themass of crystals obtained representsua yieldcorresponding to theoretical. These crystals have a melting point of.90--95- C. and, based: on an analysis of their nitrogen content, areabout 102% pure, the excess above theo-rybeing due'to slightdemethylation.

Parts Ether C 30 AlltydresinB (see Examplez1 -170 The above ingredientsare mixed and blended as-in Example 1 with the exceptionthatthe-heating' is carried out at temperatures of about 89 C; for aslightly longer period of time, thereby effecting further demethylation(condensation polymerization) of the ether and yielding a homogeneousblend which issoluble in aromatic hydrocarbons, e. g., toluene, xylene,etc. During. heating the ether'ispolymerized'. to a degreecorrespondingto the liberation of not morev than about 35% of methanoltherefrom.

- Parts Ether C 48.8 Xylene solution, of alkyd resin B. (see Ex.-ample 1. which solution is composed of 195-: parts? of solid resindissolved in 105 parts xylene 300.10

The alkyd resin solution was heated to about 80 0;, andthe ether wasadded with stirring while maintainingthetemperature at that point.Afterheati'ngfor about 15 minutes at 80 C, the temperature was graduallyraised to about 90 C. and was heldat that point for an additional periodof' about 15' minutes. The solution was then cooled, yielding a clear,homogeneous blend containing 70% of" solids dissolvedin xylene.

EXAMPLE 4 Alkyd resin D This isa typical glyceryl phthalate resinmodihad with dehydrated castor oil in an amount equivalentv to about 45%of the corresponding oil fatty acids. I

' Parts Ethel- A. l Xylene solution of alkyd. resinD (80 parts. I ofsolid resin, dissolved. in. 30 parts. of

xylene) The alkyd resin was heated to 80 C. as in Example 3-, the etheradded and the solution then heated at this temperature until thesolution on cooling remained perfectly clear. This required from 20 to40 minutes. The solution was allowed to 0001, after which 20 parts ofbutanol was added. The solution then contained 47% of solids,

EXAMPLE 5 Two different alkyd resins were used, one (resin E) of whichwas prepared by reaction in known manner of 145 parts phthalicanhydride, 3 parts fumaric acid, 100 parts glycerol, 125 parts of soyabean oil and 155 parts of soya bean oil fatty acids, and the other(resin F) by reaction of 148 parts of phthalic anhydride, 150 parts ofcastor oil and 92 parts of glycerol. 1

Blends were prepared from each of the above resins dissolved in xyleneand crystalline dimethyl ether of dimethylol urea or partialcondensation polymers thereof which had been polymerized to a degreecorresponding to the liberation of not more than about 35% of methanoltherefrom, that is, not more than about 35% demethylated. Thecrystalline dimethyl ether was substantially pure; nitrogen analysesindicated a purity of the order of 99-99.5%.

The condensation polymerization or partial demethylation of thecrystalline dimethyl ether of dimethylol urea was carried out by twodifferent procedures. In the one procedure a portion of the pure etherWas slurried in approximately eight times its weight of toluene andheated under reflux for varying lengths of time. The drop in thetemperature of the reaction mass was taken as a relative measure ofdemethylation that occurred during a given period of time. The water andfree methanol were then removed by distillation at atmospheric pressurewhile adding dry toluene thereto, the distillation being discontinuedwhen the temperature of the mass reached 111 C. The slurry was chilledto 20 C. and the condensation polymer or demethylated ether was filteredofi by means of suction and recrystallized from hot acetone. The extentof polymerization or demethylation was calculated from the nitrogencontent of the polymerized material and, also, from the results ofanalyses for methanol in the distillate.

In another procedure phthalic acid in an amount suiiicient tocatalyzethe condensation polymerization (in'all but one case 0.1% of the etherbeing polymerized) and the pure crystalline ether were added to athree-necked reaction vessel fitted with a stirrer, thermometer andcondenser. Dry-ice (solid carbon dioxide) traps were so located that anyuncondensed vapor passing through the condenser would not be lost. Themixture was heated under 15 to 17 inches of vac uum until approximately80% of the calculated methanol had been distilled off, at which timeheating was discontinued and the vacuum was increased to 27 to 28 inchesand maintained at this point until no more distillate was obtained. Thepartial condensation polymer was poured immediately into a flat-bottomedtray and air dried. The degree of polymerization or demethylation wascalculated from determinations of nitrogen and methanol as in the firstprocedure.

The partial condensation polymers or demethylated ethers prepared asabove described (seven different samples) were polymerized to a degreecorresponding to the liberation of from about 5 to about 35% of methanolfrom the ether.

; The pure, crystalline ether and the aforementioned partialcondensation polymers were then blended with xylene solutions of resinsE and F, using 20% of ether and an amount of resin solutioncorresponding to of solid resin. In preparing the blend the resinsolution in most cases was first heated on a steam bath to 86) C. Thecrystalline ether or partial condensation polymer thereof was thenadded, and heating with agitation was continued for from about 9 to 75minutes, that is, until a sample pill placed on a glass plate remainedclear for from 40 to 60 minutes. In the case of the more highlycondensed polymers, e. g., a polymer which had been condensed to adegree corresponding to the liberation of about 35% of methanol from theether, the polymer was added to the unheated alkyd resin solution andthe mixture then was heated. as above described. Longer heating periodswere required to obtain homogeneity in the case of the pure ether thanwith the partial condensation polymers thereof.

The resulting products were homogeneous blends of the alkyd resin and apartial condensation polymer of the dimethyl ether of dimethylol ureawhich had been polymerized either initially or while heating durinblending to a degree corresponding to the liberation of not more thanabout 35% of methanol from the ether. The blends were soluble in theXylene solvent and showed no separation of resin or polymer whenadditional xylene was added to replace that lost during processim or, inthe case of resin F, when an additional 20% of n-butanol was addedthereto. The xylene solutions of the blends containing resin E varied inresin solids content from about 65.5 to 63%, while the xylene-butanolsolutions of the blends containing resin F varied in solids content fromabout 46.5 to 48.5%.

When the pure dimethyl other of dimethylol.

rea was pre-polymerized to a degree corresponding to the liberation ofsubstantially more than 35%, e. g., about 37 to 40%, of methanol fromthe ether and effort was made to blend the poly mer with an alkyd resinof the kind and in the manner above described, the polymer wasincompatible with the resin and it was not possible to obtain ahomogeneous blend.

As has been described above and especially in the examples, thepracticing of my invention involves the utilization of a partialcondensation polymer of the dirncthyl ether of dimethjylol urea, whichalso may be designated as a partially demethylated ether (or a partiallydemethylated methyl ether) of dimethylol urea. The term demethylated isto be understood as describing the polymerization or condensationreaction with accompanying loss of methyl alcohol resulting from theheating of the ether to form resinous products. By partiallydemethylated ethers or methyl ethers of diinethylol urea, products aremeant which are partially polymerized but which are not sufilcientlydemethylated to produce insoluble resins. This demethylation is not tobe confused with the well-known procedure of replacing the methoxygroups in the methyl ethers with higher alkoxy groups such as butoxy.

Alkyd resins other than those hereinbefore described similarly may beblended with the dimethyl ether of dirnethylol urea or with partialcondensation polymers thereof which have been polymerized ordemethylated to the degree herein set forth to yield valuable products.As is well known, these alkyds may be prepared from polyhydric alcoholsother than glycerol, e. s.

amass g1ycols,. glycol; ethers, pentaerythritol, dipentas erythritoL,etc.-,.or from; mixtures of two or, more polycarboxylic polyhydr-icalcohols. Various. acids, e. g malonic, succiniaglutaric adipic, pimelicsuberic, sebacic citric, tr-icarballylie, benzoylphthalic', diphenic,terephthalic, etc., or.

anhyd-ides thereof, if available,- may be used in, place of all or apart of p hthalic anhydride-in; resin formulations of the kindmentioned" above; by way of illustration. If desired; phthalic acidmaybeused in place of phthalic anhydride; The; resins ma be modified by theinclusion of'variiousimonocarboxylic acids, e. g., saturated andunsaturated fatty acids, the natural resinacids, tall-.oila-ndthelike.Likewise monohydric alcohols, e. g., benzyl alcohol, cyclohexylalcohol;etc.,.

fiowed0ut:on-.asuitable surface and are allowed to. dry. Exceedinglyflexible films are obtainedv withwblends of about 20 to 30% of the pureether. or; partial condensation polymers thereof with aboutSO to: 70%ofan alkyd resinzwhich is soluble. in: an aromatic hydrocarbon, e. g.,an alkyd resin modified with; a non-oxidizing, fatty acid, as for,instance,v one prepared from glycerol, phthalic anhydride and castor oilin amounts equivalentqto 50% phthalicglyceride (glyceryl phthalate), and50% castor oil. The: others which have been partially polymerized. asdescribedabove are extremely compatible with long oil-alkyd: resins(resins containing 85% or. moreof'modifyingv fatty-acids) aspcontrastedwith the commonly used alkylatedurea resins whichordinarily are notcompatiblepwith these long oili resins.

Theblends'prepared in accordance withthe pr-esent invention are alsocharacterized by the property of 1 curing rapidly at low bakingtemeratures; Consequently these blends are especially satisfactory for:use in industrial'finishing enamels, the enamel coatings obtained beingharder. than is the case with previously used materialsof this nature.Thus, an'enamel prepared from titanium dioxide and the resin-ethersolution of Example 3 in a pigment-to-resin ratio of l to 1wasthinnedwitha solvent and-sprayed on-bare-steel panels, some of thecoatings being. baked at 250 F; and othersuat 300F. for varying. periodsof time. Sward hardness .tests indicated that" these enamel coatingswere over two times as hard as similar enamel coatings made from analkyd resin modified with a commercial butylated urea-formaldehyde resinin' place of the partial condensation polymers or demethylated othersused in practicing thepresent invention.

The; conditions for preparing the blends may bevariedsomewhat-from.those set forth above, althoughit isgenerally desired that the time andtemperature of heatingshouldbefno greater than necessary. Heating, ifcontinueditoo long;

may cause. premature gelationv with formation of nsoluble. products As.-indicated; hereinbefore;

the,- demethylated. ether (partial. condensation polymer)v is.required;, whether prepared sop;- arately or formedi during the heatingwiththe? alkydresin. Satisfactory blends areobtained with; no heating.other than; that required: to dissolvethedemethylated ether in the alkydresin;v The blends are best hardenedbyheating,.and in some cases it maybe. desirable to hasten the cure by using a small amount" of a suitableacid or. acid-forming: catalyst.

I=. claimz.

1;.The: process which comprises mixing; to.- gether; (1'); a solution ofa' soluble alkyd resin" dissolved in a solvent comprising an" aromatic;hydrocarbon and (2) a substanceof. the cl'a'ssiof: dimethyl ether of.dimethyl'ol urea and partial: condensation polymers thereof whichhave-.beeni polymerized. to a: degree. corresponding to" theliberationofnot more than about 35%. by weight: ofgmethanol from thesaid ether, andheating'tlie resulting mixture until there has beenformedaa blendawhi'cht remains clear on cooling; thesaid: substance as:present in the. said blend having; been polymerizedto a degreecorrespondingtor the? liberation of not more than about 35% by weightof. methanol from the said:ether.'

2. The process which comprises; mixing. together- (l) a solution of asoluble? alkyd resin dissolved in a. solvent comprising sin-aromatichydrocarbon and .(2) a dimethyl ether of dimethylol urea; and heatingthe resulting. mixture until' there has beenformed a blend-which remainsclearoncooling; the said dimethyl etherof di-' methylol urea as presentin the said blend hav inmbeenpolymerized to adegree correspondinwtoitheliberation of not more than about 35%- by" weightof methanol fromthe-said'ether.

3. The process whichcomprises mixing together (1') a solution ofasoluble alkyd resin dissolved in-an aromatic hydrocarbon-and (2) apartial: condensation polymer of dimethyliether ofdimethylol urea; thesaid polymer havingjbeen polymerized. to" a; degree corresponding tothe;liberation of not moreithan about'35% by weight of-methanolfrom thesaidether, and heating the resulting mixture until there has been formedablend which-remains clear on cooling;

4'. The.;p roeess which comprisespolymerizing; dimethyl ether ofdimethylol urea to a degree; correspondingto theliberation of notmorethan about.35 by weight of methanol from the saidethenadding theresulting polymer to' a' solution: of a soluble alkyd resin dissolvedin. anaromatic-hydrocarben, and-heating the result ing mixture "until.there has been formed :a blend:

which remains clear on cooling.

5; The process which comprises h'eating a'mix ture containing, (1') asolution of a soluble alkyd resin dissolved .in-a solvent comprising anaromatic-hydrocarbon and (2) aisubstance'ofthe class consistingof-dimethyl ether of dimethylol: urea and partial condensation polymersthereof which haveabeen polymerized to a degree corresponding to the:liberation of fromabout 5%: to about-30 by weightofimethanol from thesaidiether, andv continuing the heating until therehas-been formed" ahomogeneous blend; which-Js'soluble in an aromatic hydrocarbon; thesaidsubstance asi-present in the saidblendhavingbeen polymerized thedegree corresponding,to-the liberation of from about 5%.to about 39%byweight-ofmethanol from aid ether;

6-; Aprocess as in-claim .5: wherein'rtheepartiali condensation-polymer.oiz dimethyl ether; of-v dimethyloliurea'l-haszbeenpolymerized to adsrec 9 corresponding to the liberation of about of methanol from thesaid ether.

7. A process as in claim 5 wherein the alkyd resin of (l) constitutes,by weight, from 70 to 80% and the polymer of (2) from to, 20% of thesaid mixture.

8. The process which comprises mixing together 1) a xylene solution of asoya bean oil fatty acid-modified alkyd resin and (2) a partialcondensation polymer of dimethyl ether of dimethylol urea, the saidpolymer having been polymerized to a degree corresponding to theliberation of from 5 to by weight of methanol from the said ether, andheating the resulting mixture with agitation until a sample pillplacedon a glass plate remains clear for from to minutes.

9. A process as in claim 3 wherein the aromatic hydrocarbon comprisesbenzene. I

10. A process as in claim 3 wherein the aromatic hydrocarbon comprisestoluene.

11. A process as in claim 3 wherein the aromatic hydrocarbon comprisesxylene.

12. A process as in claim 3 wherein the soluble alkyd resin is a solublecastor oil fatty acidmodified alkyd resin.

13. A process as in claim 3 wherein the soluble alkyd resin is a solublesoya bean oil fatty acid-modified alkyd resin.

14. A process as in claim 3 wherein the partial condensation polymer ofthe dimethyl ether of 10 dlmethylol urea has been polymerized to adegree corresponding to the liberation of from about 5 to about 30% byweight of methanol from the said ether.

HERBERT J. WEST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,699,245 Luther Jan. 153, 19291,877,130 Hill et a1 Sept. 13, 1932 2,043,159 Eisenmann et a1. June 2,1936 2,074,814 Smith May 23, 1937 2,101,534 Edgar Dec. '7, 19372,213,921 Sorenson Sept. 3, 1940 2,254,001 Conaway Aug. 26 1941 FOREIGNPATENTS Number Country Date 320,915 Great Britain Oct. 28 1929 857,931France Apr. 29, 1940 OTHER REFERENCES Barron, Modern Plastics, pages 201and 202, pub. 1945 by John Wiley and Sons, N. Y.

Ellis, The Chemistry of Synthetic Resins, lpTub. 1935, pages 867-869,Reinhold Pub. Com,

Certificate of Correction Patent No. 2,541,139 February 13, 1951 HERBERTJ. WEST It is hereby certified that; error appears in the printedspecification the above numbered patent requiring correction as follows:

Column 7 line 7, for anhydides read (why chides; column 8, line 15 afterclass insert consisting;

and that the said Letters Patent should be read as' corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 29th div of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY, Assistant Gammz'ssz'oner of Patents.

1. THE PROCESS WHICH COMPRISES MIXING TOGETHER (1) A SOLUTION OF ASOLUBLE ALKYD RESIN DISSOLVED IN A SOLVENT COMPRISING AN AROMATICHYDROCARBON AND (2) A SUBSTANCE OF THE CLASS OF DIMETHYL ETHER OFDIMETHYLOL UREA AND PARTIAL CONDENSATION POLYMERS THEREOF WHICH HAVEBEEN POLYMERIZED TO A DEGREE CORRESPONDING TO THE LIBERATION OF NOT MORETHAN ABOUT 35% BY WEIGHT OF METHANOL FROM THE SAID ETHER, AND HEATINGTHE RESULTING MIXTURE UNTIL THERE HAS BEEN FORMED A BLEND WHICH REMAINSCLEAR ON COOLING, THE SAID SUBSTANCE AS PRESENT IN THE SAID BLEND HAVINGBEEN POLYMERIZED TO A DEGREE CORRESPONDING TO THE LIBERATION OF NOT MORETHAN ABOUT 35% BY WEIGHT OF METHANOL FROM SAID ETHER.